In this project it is proposed to study the synthesis of the first component of complement (C1) in vitro by cells derived from colonic and transitional cell carcinomas. The object will be to establish lines of cells which retain this ability as one of their stable biochemical markers. In addition to examining the molecular parameters of synthesis of C1, and/or its subunits Clq, Clr and Cls, by these cells, it is proposed to purify the new synthesized proteins by affinity chromatography and determine their structural relationship to the comparable protein isolated from serum and established cell lines. Finally, it is proposed to map the actual as well as potential sites of synthesis in humans of C1 in normal and cancer states, according to the ability of the excised cells to make C1 in vitro in primary cultures. BIBLIOGRAPHIC REFERENCES: Morris, Katherine M. (1977): Development of a culture system for transitional epithelial cells which synthesize the first component of complement (C1). Fed. Proc. 36(3), 4979. Corey, Michael; Andrews, Judith M.; and Bing, David H. (1977): Exo affinity labeling reagents. In Methods in Enzymology (Jakoby, W.B., and Wilchek, M., eds.), Academic Press, New York. In press.